An investigation is made of the potential uses of multiple cause mortality data for the study of mortality differentials for major demographic components of the U.S. population and for selected major causes of death. To date, analysis of U.S. multiple cause mortality data for 1969 has led to the determination that, for chronic degenerative diseases, there are considerable numbers of associated causes of death mentions at advanced ages. The implications of these associated cause mentions for perception of changes in cause specific mortality are found to be great. Extension of the analysis to additional years, to develop a longitudinal perspective, is planned for the near future. Substantive results have been derived which a) further characterize race and sex mortality differentials, b) yield additional insight into the black/white mortality crossover (especially for specific causes of death), c) identify the different roles of certain diseases (e.g. diabetes mellitus, selected infectious disease, atherosclerosis) as associated causes of death, d) led to the development of mathematical models of human aging and mortality useful for the study of mortality at advanced ages.